Old French joke.. so old it's new?

A rather unkempt Frenchman passes a gendarme on the street and asks, "Pardon me monsieur, is it illegal to call a gendarme a jackass?". "Yes, it certainly is.", said the policeman. "But monsieur, is it illegal to call a jackass a gendarme?" "No, I think not." said the policeman. Says the citizen, "Well then, good evening Monsieur Gendarme!"